Yarn heating apparatus



Jan. 20, 1959 v P. VAN DIJK 2,869,312

7 YARN HEATING APPARATUS Filed Jan. 30, 1956 3 Sheets-Sheet 1 &

nllMIl/AMAIlm/AllnnA/IAAAA INVENTOR ATTORNEYS Jan. 20, 1959 P, VAN D 2,869,312

YARN HEATING APPARATUS Filed Jan. 30, 1956 3 Sheets-Sheet 2 ATTORNEYS Jan. 20, 1959 P. VAN .DlJK 2,869,312

YARN HEATING APPARATUS Fild Jan. 30, 1956 3 Sheets-Sheet 3 fi'eier M4171 IN V EN TOR; gzfiiw/da, wwpw ATTORNEYS hired.

2,869,3l2 Patented Jan. 20, 1959 hoe YARN HEATING APPARATUS Pieter van Dijlr, Velp, Netherlands, assignor to American Enka Corporation, Erika, N. C., a corporation of Delaware Application January 3th, 1956, Serial No. 562,337

Claims priority, application Netherlands February 11, 1955 11 lClaims. (Cl. 57-34) This invention relates to the heating of threads or yarns and more particularly to the heating of synthetic thermoplastic threads or yarns as in the production of curled yarns as described in application Serial No. 513,442, filed June 6, 1955, by this applicant.

In said application Serial No. 513,442 there is disclosed an arrangement for heating thermoplastic yarns or threads that involves passing the same in contact with a heated surface. The yarns are moved in a more or less helical or otherwise curved path in contact with 'a smooth heated surface so that heat exchange by conduction can occur without substantial drag being imparted to the yarn. This arrangement has proved to be very satisfactory and to constitute a substantial improvement over prior arrangements in which the yarn either contacted so much surface that the resulting friction restricted its movement or else was exposed to a radiation or convection heating which was inadequate by reason of lack of uniformity. On the other hand, passing yarn over a heated surface in contact with only a relatively small portion thereof presents an economic problem in that there is heat loss from all of the heat exchange surface, whereas only a small part of that surface comes into heat exchange contact with the thread that is being processed. Furthermore, all sides of each length of yarn do not come into contact with the heated surface with resulting loss in heat energy and at least some lack of uniformity in heating effect.

It is an object of the present invention to retain the advantages of the invention described in Serial No. 513,442 while, at the same time, improving the economics of the situation by reducing the amount of heat lost from the surface that is used to impart heat to the thread.

It is proposed according to the present invention to define a smooth heated surface which surrounds or substantially surrounds the yarn to be heated and so to space the surface in relation to the yarn path that low amplitude oscillations of the yarn will result in contacting substantially all portions of the yarn surface with the heated surface.

It is an advantage of the present invention that during those intervals when the yarn is out of contact with some area of the heating surface the heat is nevertheless not lost but radiated to the yarn or thread.

The heaters to be described hereinbelow are of particular utility in the production of continuously curled yarns from thermoplastic materials by means of a false-twisting apparatus wherein the yarn is heated during the twisting operation and cooled prior to untwisting, as fully explained in said copending application, Serial No. 513,442.

Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of several embodiments thereof in conjunction with the annexed drawings wherein:

Figure l is a schematic view partially in elevation and partially in section of a tubular heating arrangement for heating running thermoplastic yarns or threads in accordance with the principles of the present invention;

Figure 2 is a view similar to Figure 1 but showing a heating path defined by a helical heating rod with the yarn passing through its core;

Figure 3 is a view similar to- Figure 1 but showing a heating path which is defined in C-section with the thread running in the included longitudinal opening;

Figure 4 is a view in section taken on the line 4-4 of Figure 3;

Figure 5 is a view similar to Figure 3 but showing a slotted heating element in which the slot spirals in the form of a helix around the heating element; and

Figure 6 is a diagrammatic View, in elevation, illustrating a continuous curling apparatus such as shown in said copending application Serial No. 513,442, as modified in accordance with one embodiment of the present in vention.

Referring now in greater detail to Figure 1, it will be noted that a yarn or thread 10 is being moved downwardly from a pair of delivery rollers 11 to a pair of takeup rollers 12. In the thread path between the rollers 11 and 12 which are vertically spaced there is disposed a hollow elongated body or tube 13 which is supported by arms 14 and 15 from a block of insulating material 16 which can be supported from a convenient part of the machine by means not shown. Electrical conduits 17 and 18 provide for an electric heating current to be applied to the tube 13, it being understood that the tube 13 is impregnated with suitable evenly distributed resistance elements for heating its inner surface. T current is led to these resistance elements from wires 17 and 18 through the arms 14 and 15. The inner surface of the tube 13 is smooth and polished. The size of the aperture in the tube 13 is so nearly the same as the diameter of the yarn it that small, low amplitude oscillations of the yarn or thread incident to its running between rollers fl and 12 will cause it to contact the inner wall of the tube 13 in very nearly all of its radii. Similarly nearly all of the surface of each length of yarn or thread is caused to contact some portion of a heating surface and the result is a considerable conservation of heat and improvement in the uniformity of heat application to the yarn or thread being treated.

In Figure 2 most of the parts shown are substantially identical to those shown in Figure l and bear like reference numerals except for the helix 19 which extends between the arms 14 and 15 in lieu of the tube 13. The helix 19 is in the form of a coil of resilient, smooth surfaced material having electric resistance elements embedded therein. ihe helix has a central core which is coaxial with the yarn path between the delivery and withdrawal rollers 1.1 and 12 and the yarn in passing through this core, comes in contact with the heated surface of the coil or helix 19. The diameter of the core of the helix i9 is so little in excess of the diameter of the yarn or thread iii that small vibrations of the yarn will result in an average uniform contact between the yarn and heater with resulting improvement in thermal efficiency and uniformity of yarn treatment.

In the modification of the invention shown in Figure 2 the upper bracket 14 is mounted on a slidable sleeve 2% which is axially movable on resistance 16 and is held in any position of adjustment by set screw 2]; whereby the tension on the coil 19 may be varied and the elfective length thereof adjusted. It will be appreciated that as the sleeve 29 is moved upwardly, the helix angle of the coil 19 will be enlarged and its core will be reduced in size to accommodate a yarn of smaller denier. Similarly, by moving slide 24? downwardly, the helix angle of the coil 19 will be reduced and the core diameter increased to accommodate a thread of larger denier.

While the diameters of the cores of the heaters 13 and 19 are required to be different for yarns of different denier it has been found that .5 mm. to .6 mm. diameter is suitable for yarns of about 70 denier.

In Figure 3 the illustrated arrangement is substantially identical to that shown in Figure 1 except that the tube 13 is replaced by a G-section element 22 which has a smooth internal surface and which is heated by resistance elements embedded therein as previously described. Because of the fact that the C member 22 does not completely surround the yarn m it is necessary to provide holding elements at the top and bottom of the yarn path through the heater. These elements are designated by reference numerals 23 and 24. The holding pieces are supported from the insulation bracket 16. The general relation of the parts in Figure 3 can be appreciated by reference to Figure 4 which virtually amounts to a plan of the apparatus from the viewpoint of the line d-4.

The form of invention shown in Figure 5 is substantially identical to that shown in Figure 3 except that instead of having a C member with a straight radial groove, the heating element is in the form of a hollow elongated body or tube having at any given point along its length a radial groove or slot, the slot itself, however, following a spiral or helical path from the top to the bottom of the heater. in Figure 5 the heater bears the reference numeral 25 and the slot thereof is designated as 26. While the conductors l7 and 18 bear polarity designations in Figures 3 and 5, it is apparent that either A. C. or D. C. heating may be employed.

While in all of Figures 1, 2, 3 and 5 the thread is shown as moving downwardly, it will be appreciated that threading in the apparatus in Figures 1 and 2 can be rather time-consuming, a thin stiff wire with a loop therein being employed. On the other hand, threading in the arrangement of Figures 3 and 5 is substantially automatic since the thread path can be established and then the running length thread pushedlaterally into the heater. If the groove at the heater is a straight one as in Figure 3 some holding means are necessary as, for example, the parts 23 and On the other hand, the helical groove as at 26 provides an easily guiding arrangement in which the threading is automatically maintained.

In general the diameters of the cores of heaters of the type herein described do not exceed 1 The grooves in the heaters and 25 under such circumstances do not exceed 0.2 mm. in width and a width of 0.15 is often used.

Attention is now directed to Figure 6 for operation of the heaters described hereinabove in combination with r a thermoplastic yarn curling apparatus of the type disclosed in said copending application Serial No. 513,442.

Yarn fit? is withdrawn from supply package 27 through suitable thread guides by feed rollers 28, From the feed rollers, the yarn passes through tensioning rollers 39, 31 and into the heater This particular heater is shown for purposes of illustration only, it being obvious that either of heaters l9, or 25 also could be used in this curling apparatus. From the heater 13 the yarn passes into and through a false twisting device 32 which is rotated by belt 33 and drive motor The device 32 imparts a false twist to yarn iii, which twist subsequently is removed prior to take-up. The false twisted yarn passes through a cooling zone and onto withdrawal godet 35, at which point substantially all of the twist is removed. Yarn leaving godet 35 is passed over guide roller 36 and collected on yarn takeup means 37.

The temporary twist imparted to yarn it? by false twist ing device 32 travels longitudinally of the to such an extent that curled yarn is contained within the heater 13. These curls are set in the yarn by the heater, and remain to a large extent after removal of the false twist. if desired, thermostat may be provided for controlling the amount ofheat to which the yarn is subjected. For

a more detailed explanation of this curling operation, attention is invited to the aforesaid copending application.

inasmuch as other embodiments will become apparent to those skilled in this art, it is intended that the scope of the present invention be limited only to the extent set forth in the following claims.

What is claimed is:

1. Apparatus for heating running lengths of yarn comprising a coil of resilient material having a longitudinal opening presenting a smooth inner surface through which yarn is passed, said inner surface extending for a major portion of the length of said coil and completely enclosing yarn passed therethrough, the diameter of said opening being not substantially greater than the diameter of the yarn to be heated, means for heating said coil, and means for passing yarn longitudinally through said opening with substantially all portions of said yarn contacting said inner surface.

2. Apparatus as set forth in claim 1 and further comprising means for adjusting the effective length of said coil in order to vary the diameter of said longitudinal opening, whereby yarn of different denier may be accommodated.

3. In a thermoplastic yarn curling apparatus including a twisting device, the improvement comprising an elongated body having a longitudinal opening presenting a smooth inner surface, the diameter of said Opening being not substantially greater than the diameter of the yarn to be curled, means for heating said elongated body, and means for passing thermoplastic yarn longitudinally through said opening in contact with substantially all portions of said inner surface while imparting twist and vibration thereto with said twisting device.

4. Apparatus as set forth in claim 3 wherein said smooth inner surface is continuous and extends the length of said elongated body.

5. Apparatus as set forth in claim 3 wherein said smooth inner surface extends for a major portion of the length of said elongated body and completely encloses yarn passed therethrough.

6. Apparatus for heating running lengths of yarn comprising an elongated body having a longitudinal opening presenting a smooth inner surface through which yarn is passed, said inner surface extending for a major portion of the length of said elongated body and completely enclosing yarn passed therethrough, the diameter of said opening beingnot substantially greater than the diameter of the yarn to be heated, means for heating said elongated body, means for passing yarn longitudinally through said opening in contact with substantially all portions of said inner surface, and means for readily adjusting the effective length of said elongated body.

7. Apparatus for heating running lengths of yarn comprising an elongated body having a longitudinal opening presenting a smooth inner surface through which yarn is passed, said inner surface extending for a major portion of the length of said elongated body and completely enclosing yarn passed therethrough, the diameter of said opening being not substantially greater than the diameter of the yarn to be heated, means for heating said elongated body, means for passing yarn longitudinally through said opening in contact with substantially all portions of said inner surface, and means for adjusting the diameter of the longitudinal opening in said clongated body.

8. Apparatus for heating running lengths of yarn comprising an elongated body having a longitudinal opening presenting a smooth inner surface through which yarn is passed, said inner surface extending for a major portion of the length of said elongated body and completely on closing yarn passed therethrough, the diameter of said opening being not substantially greater than the diameter of the yarn to be heated, means for heating said clongated body, means for passing yarn longitudinally through said opening in contact with substantially all portions of said inner surface, and means for adjusting the diameter of said longitudinal opening in response to change in the effective length of said elongated body.

9. In a thermoplastic yarn curling apparatus including a twisting device, the improvement comprising an elongated body having a longitudinal opening presenting a smooth inner surface and a radial groove, said radial groove communicating with said opening and affording access to the smooth inner surface for threading-up purposes, the diameter of said opening being not substantially greater than the diameter of yarn to be curled and the width of said groove being less than the diameter of said opening, said inner surface extending continuously for the length of said elongated body and at least substantially enclosing yarn passed therethrough, means for heating said elongated body, and means for passing thermoplastic yarn longitudinally through said opening in contact with substantially all portions of said inner surface while imparting twist and vibration thereto with said twisting device.

10. Apparatus as set forth in claim 9 and further comprising means for maintaining said yarn within said opening after threading-up through said radial groove has been accomplished.

11. Apparatus for heating running lengths of yarn comprising an elongated body having a longitudinal opening presenting a smooth inner surface through which yarn is passed and a radial groove spiraling in the form of a helix around said elongated body, said radial groove communicating with said opening and affording access to the smooth inner surface for threading-up yarn, the diameter of said opening being not substantially greater than the diameter of the yarn to be heated and the width of said groove being less than the diameter of said opening, said inner surface extending continuously for the length of said elongated body and at least substantially enclosing yarn passed therethrough, means for heating said elongated body, and means for passing yarn longitudinally through said opening in contact with substantially all portions of said inner surface.

References Cited in the file of this patent UNITED STATES PATENTS 923,425 Gin et al. June 1, 1909 2,204,603 Kline et al. June 18, 1940 2,345,032 Castricum Mar. 28, 1944 2,440,159 Stanley Apr. 20, 1948 2,462,607 Browne Feb. 22, 1949 2,520,532 Dalgleish et al Aug. 29, 1950 2,673,385 Williamson et al. Mar. 30, 1954 2,717,302 Egee et al. Sept. 6, 1955 2,761,272 Vandamme et al. Sept. 4, 1956 2,793,277 Gehrke et al. May 21, 1957 2,803,105 Stoddard et al. Aug. 20, 1957 

